|You override being a shadow member by mount/over=shadow_member.|
use HELP MOUNT /OVER to read the /over=shadow_member entry.
If You do it, then at the next mount as a shadow member it will do a full copy.
Otherwise if it is really a shadowset member, then simply mount it into the shadowset where it belongs and it will be unlocked.
So You and nobody else know the history of the disk: if it is just a disk inherited and added to Your system, then it is probably best to INIT the volume to get rid of any previous volume group membership, and start with a fresh empty volume.
Joseph Huber, http://www.huber-joseph.de